In large assembled structures, for example the housing structure of an aircraft jet engine, when a two piece fastener assembly, for example a nut and bolt assembly is lost from a fastener hole in the structure it is often very difficult to replace with a similar 2 piece fastener. The fastener hole missing the fastener assembly is often easily accessible from the exterior of the structure. However, in order to assemble a two piece fastener assembly in the fastener hole it is also necessary to access the fastener hole from the interior of the structure. This is often not possible without a major disassembly of the structure to access the fastener hole from the interior of the structure.
To address the problem of accessing a fastener hole from an interior of a structure without requiring a major disassembly of the structure, robotic crawlers could be developed. Such a robotic crawler would have the ability to hold to an interior surface of a wall of the structure as the crawler moves across the wall interior surface to position a fastener piece, for example a nut held by the crawler in alignment with the fastener hole. Once the nut was positioned in alignment with the fastener hole by the robotic crawler, a bolt could be inserted through the fastener hole and threaded into the nut to replace the fastener assembly missing from the fastener hole.
However, such robotic crawlers are disadvantaged in that they are expensive to manufacture. Additionally, the size of the robotic crawler may limit its access to areas inside an assembled structure such as a jet engine housing structure. Still further, operation of a robotic crawler to position a fastener piece in alignment with a fastener hole of a structure such as a jet engine housing structure requires a skilled operator for the crawler.